Garry's Law 

"When you tell people your goals you don’t achieve them." - Garry Newman.

Since I'm unable to post a link to his blog I will quote him:
I’ve made this point before, years and years ago. But I couldn’t find where I wrote it. So here it is again.

There’s a lot of reasons you shouldn’t tell people your idea. They might not like it. They might like it and steal it. They might convince you it’s a bad idea. They might convince you to change it into something else.

The biggest reason to keep your goal a secret is that once you start talking about something you’re going to do you don’t have to do it. In your mind you will have already done it. Their positive reaction to your idea is the reward. Actually doing the work seems stupid at that point. There’s no big prize at the end of actually doing it because it’ll be exactly what everyone expected. Which means you probably won’t do it.

And then it reflects badly on you. Next time you have an idea people will be slightly less enthusiastic because none of you ideas ever turn into anything. They’re just ideas.

Much better to get your head down and then show them your idea. More work for a bigger pay off.

After his blogpost, his community called 'Facepunch' decided to call this principle "Garry's Law".

Notch: Hey guys, look what we're working on!
*Notch shows 0X10C*

- A while later -

Notch: Nah imma quit dis.
Public audience: ERMAHGERD, GARRY'S LAW!!!!1!!!!!111!!one!!!!!

Garry's Law by Zerfox September 18, 2013